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7807
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The laws of thought are true, but they are not the axioms of logic [Bolzano, by George/Van Evra]
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Full Idea:
Bolzano said the 'laws of thought' (identity, contradiction, excluded middle) are true, but nothing of interest follows from them. Logic obeys them, but they are not logic's first principles or axioms.
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From:
report of Bernard Bolzano (Theory of Science (Wissenschaftslehre, 4 vols) [1837], §3) by George / Van Evra - The Rise of Modern Logic
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A reaction:
An interesting and crucial distinction. For samples of proposed axioms of logic, see Ideas 6408, 7798 and 7797.
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9618
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Bolzano wanted to reduce all of geometry to arithmetic [Bolzano, by Brown,JR]
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Full Idea:
Bolzano if the father of 'arithmetization', which sought to found all of analysis on the concepts of arithmetic and to eliminate geometrical notions entirely (with logicism taking it a step further, by reducing arithmetic to logic).
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From:
report of Bernard Bolzano (Theory of Science (Wissenschaftslehre, 4 vols) [1837]) by James Robert Brown - Philosophy of Mathematics Ch. 3
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A reaction:
Brown's book is a defence of geometrical diagrams against Bolzano's approach. Bolzano sounds like the modern heir of Pythagoras, if he thinks that space is essentially numerical.
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9830
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Bolzano began the elimination of intuition, by proving something which seemed obvious [Bolzano, by Dummett]
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Full Idea:
Bolzano began the process of eliminating intuition from analysis, by proving something apparently obvious (that as continuous function must be zero at some point). Proof reveals on what a theorem rests, and that it is not intuition.
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From:
report of Bernard Bolzano (Theory of Science (Wissenschaftslehre, 4 vols) [1837]) by Michael Dummett - Frege philosophy of mathematics Ch.6
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A reaction:
Kant was the target of Bolzano's attack. Two responses might be to say that many other basic ideas are intuited but impossible to prove, or to say that proof itself depends on intuition, if you dig deep enough.
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17265
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Philosophical proofs in mathematics establish truths, and also show their grounds [Bolzano, by Correia/Schnieder]
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Full Idea:
Mathematical proofs are philosophical in method if they do not only demonstrate that a certain mathematical truth holds but if they also disclose why it holds, that is, if they uncover its grounds.
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From:
report of Bernard Bolzano (Theory of Science (Wissenschaftslehre, 4 vols) [1837]) by Correia,F/Schnieder,B - Grounding: an opinionated introduction 2.3
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A reaction:
I aim to defend the role of explanation in mathematics, but this says that this is only if the proofs are 'philosophical', which may be of no interest to mathematicians. Oh well, that's their loss.
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22064
|
Fichte's logic is much too narrow, and doesn't deduce ethics, art, society or life [Schlegel,F on Fichte]
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Full Idea:
Only Fichte's principles are deduced in his book, that is, the logical ones, and not even these completely. And what about the practical, the moral and ethical ones. Society, learning, wit, art, and so on are also entitled to be deduced here.
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From:
comment on Johann Fichte (The Science of Knowing (Wissenschaftslehre) [1st ed] [1794]) by Friedrich Schlegel - works Vol 18 p.34
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A reaction:
This is the beginnings of the romantic rebellion against a rather narrowly rationalist approach to philosophy. Schlegel also objects to the fact that Fichte only had one axiom (presumably the idea of the not-Self).
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9185
|
Bolzano wanted to avoid Kantian intuitions, and prove everything that could be proved [Bolzano, by Dummett]
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Full Idea:
Bolzano was determined to expel Kantian intuition from analysis, and to prove from first principles anything that could be proved, no matter how obvious it might seem when thought of in geometrical terms.
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From:
report of Bernard Bolzano (Theory of Science (Wissenschaftslehre, 4 vols) [1837]) by Michael Dummett - The Philosophy of Mathematics 2.3
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A reaction:
This is characteristic of the Enlightenment Project, well after the Enlightenment. It is a step towards Frege's attack on 'psychologism' in mathematics. The problem is that it led us into a spurious platonism. We live in troubled times.
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13231
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Explanatory proofs rest on 'characterizing properties' of entities or structure [Steiner,M]
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Full Idea:
My proposal is that an explanatory proof makes reference to the 'characterizing property' of an entity or structure mentioned in the theorem, where the proof depends on the property. If we substitute a different object, the theory collapses.
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From:
Mark Steiner (Mathematical Explanation [1978], p.34)
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A reaction:
He prefers 'characterizing property' to 'essence', because he is not talking about necessary properties, since all properties are necessary in mathematics. He is, in fact, reverting to the older notion of an essence, as the core power of the thing.
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22060
|
The Self is the spontaneity, self-relatedness and unity needed for knowledge [Fichte, by Siep]
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Full Idea:
According to Fichte, spontaneity, self-relatedness, and unity are the basic traits of knowledge (which includes conscience). ...This principle of all knowledge is what he calls the 'I' or the Self.
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From:
report of Johann Fichte (The Science of Knowing (Wissenschaftslehre) [1st ed] [1794]) by Ludwig Siep - Fichte p.58
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A reaction:
This is the idealist view. He gets 'spontaneity' from Kant, which is the mind's contribution to experience. Self-relatedness is the distinctive Fichte idea. Unity presumably means total coherence, which is typical of idealists.
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22016
|
The self is not a 'thing', but what emerges from an assertion of normativity [Fichte, by Pinkard]
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Full Idea:
Fichte said the self is not a natural 'thing' but is itself a normative status, and 'it' can obtain this status, so it seems, only by an act of attributing it to itself. ...He continually identified the 'I' with 'reason' itself.
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From:
report of Johann Fichte (The Science of Knowing (Wissenschaftslehre) [1st ed] [1794]) by Terry Pinkard - German Philosophy 1760-1860 05
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A reaction:
Pinkard says Fichte gradually qualified this claim. Fichte struggled to state his view in a way that avoided obvious paradoxes. 'My mind produces decisions, so there must be someone in charge of them'? Is this transcendental?
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17264
|
Propositions are abstract structures of concepts, ready for judgement or assertion [Bolzano, by Correia/Schnieder]
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Full Idea:
Bolzano conceived of propositions as abstract objects which are structured compounds of concepts and potential contents of judgements and assertions.
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From:
report of Bernard Bolzano (Theory of Science (Wissenschaftslehre, 4 vols) [1837]) by Correia,F/Schnieder,B - Grounding: an opinionated introduction 2.3
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A reaction:
Personally I think of propositions as brain events, the constituents of thought about the world, but that needn't contradict the view of them as 'abstract'.
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12232
|
A 'proposition' is the sense of a linguistic expression, and can be true or false [Bolzano]
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Full Idea:
What I mean by 'propositions' is not what the grammarians call a proposition, namely the linguistic expression, but the mere sense of this expression, is what is meant by proposition in itself or object proposition. This sense can be true or false.
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From:
Bernard Bolzano (Theory of Science (Wissenschaftslehre, 4 vols) [1837], Pref?)
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A reaction:
This seems to be the origin of what we understand by 'proposition'. The disputes are over whether such things exists, and whether they are features of minds or features of the world (resembling facts).
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22065
|
Fichte reduces nature to a lifeless immobility [Schlegel,F on Fichte]
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Full Idea:
Fichte reduces the non-Ego or nature to a state of constant calm, standstill, immobility, lack of all change, movement and life, that is death.
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From:
comment on Johann Fichte (The Science of Knowing (Wissenschaftslehre) [1st ed] [1794]) by Friedrich Schlegel - works vol 12 p.190
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A reaction:
The point is that Fichte's nature is a merely logical or conceptual deduction from the spontaneous reason of the self, so it can't have the lively diversity we find in nature.
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